In a printer of a serial recording system, a continuous sheet is repeatedly fed/stopped and conveyed with a predetermined dimension unit (conveyance step width). Moreover, a plurality of pages are continuously printed on the continuous sheet by a print head, and a joint between the pages is cut away with a cutter on a downstream side of the print head.
The cutter for use herein performs a cut operation while the continuous recording sheet stops. Since the position of the cutter is fixed, a cut position of the sheet is provided every conveyance step width.
Since the cut position of the sheet is discontinuously determined at an interval of the conveyance step width in this manner, it is impossible to cut the sheet within the conveyance step width. Therefore, when a cut dimension or size of the sheet does not accurately agree with a multiple of a conveyance step width (α), the cut sheet having such dimension cannot be obtained. The sheet must be cut before or after the desired dimension. Thus obtained cut sheets have different dimension. Thus obtained cut sheets have different dimension. That is, a dispersion is generated in the dimension of the cut sheet.
For example, it is assumed that the image is recorded by eight divisions (eight paths) in a sub scanning direction by an ink jet head including 512 nozzles at 400 dpi. In this case, the sheet is fed by a unit of (512/400)÷8 inches (=0.16 inch=4.064 mm=α). On the other hand, a boundary of page sometimes comes midway in the width (conveyance step width) α. In this case, to cut a correct page dimension, the sheet has to be cut midway in the width α. However, it has heretofore been impossible to cut the sheet in such a position.
Moreover, when a length of the image to be recorded on each page in the conveyance direction does not agree with a multiple of the conveyance step width (i.e., feeding pitch of the sheet), the position of the recording image in each page is displaced from the position of the recording image in the preceding and/or next page. Therefore, the length of the margin surrounding the recorded image varies in the contiguous pages. The marginal length disperses in each of pages.
The dispersion of the marginal dimension does not usually raise any problem in a printer having a large size such as an AO size. The difference of marginal dimension is not conspicuous. However, to print a small size such as an A4 size and picture size (a length especially of a sheet short side is 89 mm), the dispersion of the marginal dimension is recognized as a conspicuous error.
Further, by repeating displacement of the recorded image in the contiguous pages, the recorded image will intrudes into the next page. To obtaining a cut sheet containing the entire recorded image therein, the continuous recording sheet is further conveyed by one conveyance step width, i.e., is fed one more feeding pitch, before the sheet is cut by the cutter. The obtained cut sheet has a different and longer dimension than that of the ordinary cut sheet. This causes the dispersion in the cut dimension of the printed and cut sheets. Therefore, edges of bundled printed sheets are irregularly aligned.
It has been proposed that the reduction of a division width of a sub scanning direction in a last divided recording portion of the image in order to reduce the dispersion of the cut dimension of the sheet. However, in this case, since the division width of the sub scanning direction is small, that is, since the feeding pitch of the sheet is small, a streak (banding) is generated in a main scanning direction and an image quality is easily deteriorated. A problem occurs that a recording time (print time) lengthens.
There is another proposed method of moving a terminal end (cut position) of a recording page to a fixed position of a cutter blade and cutting the page, every time one sheet of image is recorded. However, in this case, a tip end of sheet has to be returned to the recording position of the print head before starting the recording of the next page. Therefore, a time required for the printing lengthens, additionally a conveyance mechanism of the sheets becomes complicated, and also the sheet is drawn/returned resulting in a drop of reliability of the operation.